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Picture Rocks Cooling Heating & Plumbing Blog

Why Aren’t the Burners in My Furnace Lighting?


It’s getting pretty late in the winter, but it isn’t spring yet. It’s not quite time to be done with our heating systems. We’ll still need them a bit longer! So if your furnace’s burners aren’t lighting, you’ll need to get that fixed right away. What can cause this? Here are some of the possibilities.

Pilot Problems

Today’s gas furnaces don’t use pilot lights, but if you have an older furnace, you might still have one. This needs to stay lit at all times, and if it goes out, it needs to be relit. Make sure to follow the directions in your owner’s manual carefully so that you can relight the pilot safely. If you can’t manage it, or the pilot light keeps going out after you relight it, you’ll need furnace repair in Marana, AZ.

Electronic Ignition Problems

The modern alternative to the pilot light is the electronic ignition system, which creates a spark to light the gas rather than keeping a flame standing at all times. If this system malfunctions or fails, the burners won’t light. A heating repair technician can determine exactly what went wrong and repair it, or replace the igniter if necessary.

Flame Sensor Problems

The flame sensor does a complex and important job. A small amount of gas is used to light a flame. Then, more gas is released once the flame is properly lit. Without a flame, it would be dangerous to release more gas—it would just be a gas leak—so the flame sensor is necessary for determining that it’s safe to release enough gas to light the burners.

Despite how critical this job is, the flame sensor itself is an extremely simple component. It’s just a metal rod! How does that detect a flame? It uses itself, and the flame, to complete an electrical circuit which allows the gas to flow. If there’s no flame, the circuit is incomplete. 

But because of all the combustion it’s exposed to, a layer of carbon can build up over the sensor. Carbon is a great insulator and will prevent the circuit from being completed even when there is a flame! This will stop the burners from being lit. A technician can disassemble this circuit and clean the sensor so it will work properly again.

Burner Problems

It’s possible that something is truly wrong with the burners that requires repair or replacement of one or more of these components. It’s also possible that, like the flame sensor mentioned above, the burners are simply dirty. An accumulation of carbon may need to be removed to allow them to light.

Gas Valve Problems

In order for the gas to flow, the gas valve needs to be able to open and close smoothly. It usually does this job perfectly, but on occasion, it can get stuck in one position. If this is your problem, you might be able to hear clicking sounds coming from your furnace. 

Thermostat Problems

Finally, your burners won’t come on if the thermostat doesn’t tell them to! This could happen if you’ve accidentally nudged a switch into the “fan only” position, so check that your thermostat’s settings are correct before calling for repairs. But it can also be due to loose or disconnected wiring or a miscalibration, which would need professional attention.

Whatever the cause, prompt repair can get your burners lit and your home toasty again so you can stay warm for the rest of the winter.

Contact Picture Rocks Cooling, Heating & Plumbing today to schedule an appointment with our professionals.

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